In the background of environment protection and power-saving awareness, the requests for new energy electric vehicles and their on-board charger(OBC) keep growing. As one of the important components in the OBC module, magnetics is getting more and more attention accordingly. The magnetics integration of differential mode (DM) and com-mon mode(CM) chokes for a 3-phase 4-wire (3P4W) electromagnetic interference(EMI) filter used in OBC is theoretically analyzed and studied. Based on the analysis and comparison of the background of power supply applications, the inte-gration principle for DM and CM chokes, and the available integration schemes in industry and academia, an integration of DM and CM chokes for 3P4W with quasi-cross DM magnetic branches is proposed. Through the magnetic flux simula-tion analysis, electrical characteristics under DC-bias and the on-board tested data, the effect of the magnetics integra-tion scheme was proved, i.e., it can obviously decrease the DC-bias on DM magnetic branches in the case of unbalanced 3-phase current and effectively improve the anti-EMI performance of power supply.